Patients in hospitals or otherwise under medical care frequently require a continuous supply of fluid injected directly into the body, the most commonly known procedure being intravenous feeding. A hollow needle secured to the patient, usually at the hand or wrist area, is connected to a tube which carries a nutrient fluid mixture and perhaps other medicinal fluids from a supply container that is usually suspended on a stand, such that fluid flow into the patient is effected under the influence of gravity.
This invention relates to method and apparatus for insulating warmed intravenous fluid from ambient temperature losses to minimize and prevent a significant decrease in warmed I.V. fluid temperature as the I.V. fluid passes through the I.V. administration set and tubing to a patient.
Sterile fluids for intravenous (I.V.) administration into the human body often require warming from ambient temperature (20 degree C.) to approximate body temperature (37 degree C.) before or during their introduction. The purpose of warming I.V. fluids and chilled blood to approximately 37 degree C. is to improve the maintenance of body temperature. This is especially true during anesthesia and surgery when body temperature falls due to surgical exposure of large body surface areas to ambient temperature and interference of normal body thermo-regulatory mechanisms by anesthesia. This results in the patient becoming cool, often shivering post-operatively; patients may stay longer in the recovery room to recover from hypothermia.
Current technology to provide warm I.V. fluids to patients undergoing anesthesia and surgery are in-line fluid warmers and external fluid warmers. In-line fluid warmers heat I.V. fluid up to body temperature by applying heat directly (via an in-line heating element) to the I.V. fluid as it passes from the I.V. fluid reservoir (glass bottle or plastic bag) at ambient temperature to the patient. The in-line heating elements for in-line I.V. fluid warmers are disposable and costly per patient use.
External I.V. fluid warmers may be used to heat the I.V. fluid (in bulk) to 37 degree C. before administration to the patient. The external I.V. fluid heaters heat 6 to 20 separate I.V. fluid containers (plastic bags or glass bottles) simultaneously to approximately body temperature. The warmed I.V. bags are removed from the external heater as needed and placed into use, generally by hanging them from an I.V. pole and connecting to an administration set (which usually consist of drip chamber, I.V. tubing, roller clamps and connectors) and finally attaching to the patient""s I.V. cannula. After hanging, the warmed I.V. fluid bags cool down approaching ambient temperature as time goes by, and further lose temperature as the warmed I.V. fluid passes through un-heated I.V. tubing and administration set at ambient temperature. Slower I.V. fluid flow rates result in cooler delivered I.V. fluids to the patient because the I.V. fluid cools down with time while passing through the interconnecting tubing of the administration set, exposed to ambient temperature, before entering the patient. This cooling effect with low I.V. fluid flow rates also affects any in-line fluid warmers during passage through the I.V. tubing from in-line warming device to patient.
Advantages exist in preventing heat loss of pre-warmed I.V. fluids during flow through I.V. administration tubing from an I.V. reservoir bag or bottle to the patient""s anatomic administration site. The use of pre-warmed I.V. fluids are a practical, less expensive and more efficient method of administering warm I.V. fluids to patients as opposed to in-line I.V. fluid warmers. Compared to in-line I.V. fluid warmers, pre-warned I.V. fluids are: 1) less expensive, 2) less complicated to set up and administer, and 3) less bulky because of not requiring an active heating source to be placed near the patient.
It is an object of this invention to provide flexible insulated I.V. tubing from the I.V. reservoir bag or bottle to the patient anatomic administration site.
It is a further object of this invention to use a light-weight insulated I.V. tubing material to provide less bulk near the patient and optionally include the ability to visualize air bubbles in the I.V. tubing.
Other objects and advantages will become apparent in light of the attached drawings and description of the invention presented hereinbelow and the appended claims.
In accordance with one embodiment of the present invention, there is disclosed an insulated I.V. administration tubing.
Another embodiment of the invention provides a patient""s I.V. administration tubing comprised of two flexible, optionally visually-clear or transparent, tube-like, concentric channels separated by an insulating space. This tubing includes an outer channel that forms an exterior covering. The outer channel optionally may be separated from the inner channel by an insulating space. The outer channel may also optionally provide a separation aligned with and attached to the inner channel by means of central support structures. Such an attachment of the inner and outer channel separations by means of the central support structures provides centering and maintains the inner channel within the outer channel.
Additional ancillary centering support structures may aid in keeping the inner channel centered and maintained within the outer channel when the course of the patient""s I.V. tubing: 1) acutely bends 2) lays against other surfaces, or 3) is physically pressed against or placed upon by other devices or structures in the immediate environment. Additionally, the outer channel of the tubing of this embodiment of the present invention may be closed to or sealed to the inner channel at each end to prevent air movement and heat loss by convection.